The present invention relates to a bearing housing and roller shaft seal. More particularly, the bearing housing and roller shaft seal of the present invention are intended to increase the capacity of the bearing housing and seal to compensate for axial movement in the roller.
A polyurethane end cap assembly for the roller tube of conveyor rollers is described in Australian Patent 686028 to the present applicant. The end cap assembly is described as comprising an end cap body which is interference fitted within an end of a roller tube and in which is received a bearing. The bearing is fitted within the end cap body from an inner side of the end cap body, thereby minimising the exposure of the bearing to dust and dirt from outside the conveyor roller. A removable inner seal means is snap fitted within the end cap body behind the bearing and acts to seal the bearing from any dust and dirt within the conveyor roller. The outer face of the bearing is sealed by an inner collar portion of the end cap body which projects inwardly towards the roller shaft and on which are provided a pair of arms. One of these arms engages a radially inner race of the bearing whilst the other engages the shaft.
In such an arrangement, dust and dirt from outside the end cap assembly must penetrate past both arms to reach the bearing. In addition, the space between the arms, and the space between the neck portion of the end cap body and the bearing constitute a grease trap to further prevent the passage of dust and dirt to the bearing. Further, a dust seal is press fitted to the roller shaft externally to the end cap body and projections provided thereon engage lightly an outer surface of the end cap body allowing free rotation of one relative to the other, but providing an initial barrier to the ingress of dust and dirt to the end cap assembly.
Whilst the end cap assembly described in Australian Patent 686028 operates well to prevent the ingress of dust and dirt to the bearing housed within the end cap body, the manner in which the various seals are effected does not allow the end cap assembly to effectively deal with axial movement generated within the conveyor roller through relative movement between the roller and shaft. Such movement tends to decrease the efficiency of the various seals, as the arms that impinge upon either the shaft or the inner race of the bearing are fairly thick and rigid and impinge upon their respective surface at a steep angle. This requires precise manufacturing tolerances when constructing the end cap assembly in an effort to establish and maintain the various seals.
Axial movement and/or radial loads within the conveyor roller can act to either decrease the effectiveness of a seal or increase drag between the stationary inner race of the bearing or the roller shaft, and the rotating end cap body.
The bearing housing and roller shaft seal of the present invention have as one object thereof to substantially overcome the above problems associated with the prior art, or to at least provide a useful alternative thereto.
The preceding discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia as at the priority date of the application.
Throughout this specification, unless the context requires otherwise, the word xe2x80x9ccomprisexe2x80x9d, or variations such as xe2x80x9ccomprisesxe2x80x9d or xe2x80x9ccomprisingxe2x80x9d will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers including method steps.
In accordance with the present invention there is provided a bearing housing comprising a body portion proportioned to receive therein a bearing, the body portion having an inwardly projecting neck portion in turn provided with a terminal portion having an annular bearing seal rim and an annular shaft seal rim, wherein the terminal portion of the neck portion is flexible relative to the remainder of the body portion.
The or each bearing seal rim preferably curves rearwardly and inwardly to impinge upon an inner race of a bearing held within the bearing housing. Further, the or each shaft seal rim preferably curves forwardly and inwardly to impinge upon a roller shaft about which the bearing housing is rotatably arranged.
Still preferably, each seal rim impinges upon its respective seal surface at a gentle or low angle, this low angle being facilitated by the curved nature of the seal rims. The low angle is preferably below 90xc2x0. Still further preferably, the low angle is below 45xc2x0.
An annular inner seal means is preferably press or snap fitted into a rear face of the bearing housing and forms a seal with the inner race of the bearing.
In accordance with the present invention there is further provided an end cap assembly for the roller tube of a roller conveyor, the end cap assembly comprising a body portion, an annular inner seal means, a bearing, and an annular dust seal, wherein the body portion is proportioned to receive therein the bearing, the body portion having an inwardly projecting neck portion in turn provided with a terminal portion having an annular bearing seal rim and an annular shaft seal rim, wherein the terminal portion of the neck portion is flexible relative to the remainder of the body portion.
The or each bearing seal rim preferably curves rearwardly and inwardly to impinge upon an inner race of a bearing held within the bearing housing. Further, the or each shaft seal rim preferably curves forwardly and inwardly to impinge upon a roller shaft about which the bearing housing is rotably arranged.
Still preferably, each seal rim impinges upon its respective seal surface at a gentle or low angle, this low angle being facilitated by the curved nature of the seal rims. The low angle is preferably below 90xc2x0. Still further preferably, the low angle is below 45xc2x0.
The annular inner seal means is preferably press or snap fitted into a rear face of the bearing housing and forms a seal with the inner race of the bearing. The dust seal preferably abuts an outer surface of the body portion. Still preferably, a labyrinth seal is formed thereby.